Dynamic-static shaft seal

Abstract

A seal engageable with the outer surface of a shaft and fittable within an inwardly open groove formed in a housing between a high-pressure zone and a low-pressure zone has a cup packing integrally bonded to a supple pressure-distributing ring. The packing is of asymmetrical section and is formed with a radially extending flange and with a lip extending from one axial side of the flange toward the high-pressure zone with the inner face of the lip lying resiliently against the outer surface of the shaft. The pressure-distributing ring has an end surface bonded to the one side of the flange, an inner periphery formed with a recess snugly receiving and bonded to the outer face of the lip, and an outer periphery resiliently engaging the interior of the housing groove. A nonresilient antiextrusion ring is received in the packing at the other axial side of the packing.

I claim: 
     
       1. A sealing assembly comprising a shaft, a housing surrounding said shaft and formed with an inwardly open annular groove, and a seal received in said groove and surrounding said shaft, said seal being disposed in said housing between a high-pressure zone and a low-pressure zone formed therein, said seal comprising: a cup packing of asymmetrical section and formed with radially extending flange and with a frustoconical lip extending from one axial side of said flange toward said high-pressure zone and having an inner face resiliently engageable with the outer surface of said shaft;   a supple pressure-distributing ring having an end surface bonded to said one side of said flange, an inner portion formed with a recess snugly receiving and bonded to the outer face of said lip, said recess having a frustoconical wall bonded to said outer face, a substantially cylindrical outer periphery resiliently engaging with and bottoming in the interior of said groove, and a substantially cylindrical inner periphery engaging said outer surface of said shaft, said lip having an inner face inclined inwardly toward said inner periphery and terminating flush therewith; and   a nonresilient ring received in said packing at the other axial side thereof, said presssure-distributing ring retaining said packing out of engagement with the bottom of said groove and holding most of said lip out of engagement with said outer surface in the absence of a pressure differential across said zones.   
     
     
       2. The assembly defined in claim 1 wherein said packing and said pressure-distributing ring are elastomeric. 
     
     
       3. The assembly defined in claim 2 wherein the coefficient of friction between said pressure-distributing ring and said groove is greater than the coefficient of friction between said pressure-distributing ring and said packing on one side and said shaft on the other. 
     
     
       4. The assembly defined in claim 2 wherein said pressure-distributing ring has a radial thickness greater than the radial distance between said outer surface of said shaft and the base of said groove in an uncompressed state of said pressure-distributing ring. 
     
     
       5. The assembly defined in claim 4 wherein said pressure-distributing ring has another end surface formed at said peripheries with chamfers. 
     
     
       6. The assembly defined in claim 2 wherein said groove has an axial length greater than the combined axial length of said packing and said pressure-distributing ring.